Melatonin secretion is increased in children with severe traumatic brain injury

Background: Traumatic brain injury (TBI) is a leading cause of death and disability in children. Oxidative stress plays a significant role in brain damage and melatonin exhibits both direct and indirect antioxidant effects. The primary aim of the present study was to evaluate serum melatonin levels in children with severe TBI in comparison to critically ill children admitted to the Pediatric Intensive Care Unit for conditions other than TBI. Methods: Twenty-four children were evaluated, equally divided into severe TBI and no-TBI. Blood samples for serum melatonin analysis were collected at 22:00, 01:00, 03:00, 05:00, 08:00, and 12:00. Results: Mean serum melatonin peaks in children of the TBI group were higher compared to the values of no-TBI critically ill children (495 +/- 102 vs. 294 +/- 119 pg/mL, p = 0.0002). Furthermore, the difference was even more significant in comparison to values reported in literature for healthy age-matched children (495 +/- 102 vs. 197 +/- 71 pg/mL, p < 0.0001). Conclusion: This study has shown that endogenous serum melatonin levels dramatically increase in children after severe TBI. This elevation is likely to represent a response to oxidative stress and/or inflammation due to severe head injury.